msm: kgsl: Add GPU speed-bin vector support for A3XX

Add support to read GPU speed-bins from the different
registers for A3xx devices to load different
GPU power levels.

Change-Id: I1ee7e82f1f9bea7c4a2862930bea83e427a6090b
Signed-off-by: c_masira <masira@codeaurora.org>